Scheduled Transport Services Research Articles

Partial and complete replanning of an intermodal logistic system under disruptions

The exclusive and excessive use of long-distance road transportation is not suitable way to reduce the negative environmental impacts of logistics systems. Intermodal transport, combining road with other transport modes, has the potential to reduce both operating costs and carbon footprints. One of the reasons for the low share of intermodal transport is its requirement for the coordination of scheduled transport services that can result in reducing reliability in case of disruptions due to the arrival of new shipment orders, fluctuations in shipment quantities, delays, and service cancellations within the network. This calls for reliable and efficient algorithms to replan the shipments’ distribution. In this paper, the replanning problem is formulated as a path-based multi-commodity network flows. We provide two different network topologies, one of which is based on a time–space network, while the other embeds time aspect in a highly scalable alternative structure to large transportation networks. We propose a column generation method whose pricing sub-problems are presented as resource constrained shortest path problem solved via a tailored label-correcting algorithm. We look at the pros and cons of complete and partial replanning in case of disruption and provide managerial insights for intermodal networks. An extensive set of computational experiments is presented on realistic instances being generated with the consultation of our industrial partners for a logistic network including railways, waterways, and roads. The promising outcomes validate the efficiency of the proposed approach that can be easily adjusted to real-time intermodal logistic replanning.

Efficiency and Sustainability of Regional Aviation on Insular Territories of the European Union: A Case Study of Public Service Obligations on Scheduled Air Routes among the Balearic Islands

Mediterranean islands of the European Union (EU) have traditionally suffered from a lack of regularity in supplying public transportation due to the high seasonality of the demand for scheduled transport services. The insular fact forces people and goods to be carried either by sea or air, and therefore needs to actively stimulate interest in operating specific routes by proper carriers. As regional economies on insular territories also have a tight dependence on tourism, it is vital to achieve an appropriate balance between the need for effective public transportation and sustainable means of transport. This paper aims to provide an approach to the Public Service Obligation (PSO) system imposed on air routes serving the regional transport needs of the Balearic Islands. This study has analyzed data relating to freight and passenger traffic in the period between 2004 and 2019 from scheduled air services linking Palma de Mallorca with Ibiza and Menorca, as well as those between Menorca and Ibiza, and to their respective short-sea links. Results obtained in the research suggest that PSO impositions, together with significant improvement in the resident subsidy schema (from 50% to 75%), have recently led to a sharp increase in the demand for passenger air services on these routes; thus, avoiding the tender for the award of a public contract. However, it has led to a dramatic fall of freight transport on air routes concerned, as such, public intervention on the air market has only sought to ensure the mobility of passengers.

Real-time disruption management approach for intermodal freight transportation

The share of intermodal transportation, which is often considered as a sustainable transportation alternative, is rather low compared to road transportation. There are several reasons for this situation, including the increased need for coordination of scheduled transport services and the reduced reliability of intermodal transport chains in case of disruptions. In this regard, developing an advanced algorithmic approach can help to handle real-time data during the execution of transportation and react adequately to detected unexpected events. In this way the reliability of intermodal transport can be increased, which might help to increase its usage and to minimize the negative externalities of freight transportation. This paper proposes a novel real-time decision support system based on a hybrid simulation-optimization approach for intermodal transportation which combines offline planning with online re-planning based on real-time data about unexpected events in the transportation network. For each detected disruption, the affected services and orders are identified and the best re-planning policy is applied. The proposed decision support system is successfully tested on real-life scenarios and is capable of delivering fast and reasonably good solutions in an online environment. This research might be of particular benefit to the transport industry for using advanced solution methodologies and give advice to transportation planners about the optimal policies that can be used in case of disruptions.

Collaborative Fleet Deployment and Routing for Sustainable Transport

Efficient multi-modal transportation in the hinterland of seaport terminals depends on consolidation of container volumes in support of frequent services of high capacity means of transport, such that sustainable multi-modal transport can compete with uni-modal road transport in cost and time. The tactical design of barge scheduled transport services involves fleet selection and routing through the inland waterway network. The resulting network service design should meet expected demand and service time requirements set by the shippers. We develop a tight MILP formulation for the Fleet Size and Mix Vehicle Routing (FSMVRP) especially adapted for the Port-Hinterland multi-modal barge network design. Also, an analytical model is developed to help understand important design trade-offs made. We consider the case of horizontal cooperation of dry port container terminals that share capacity. Our results show that in case of cooperation, both cost savings and service levels are improved, and allow for sustainable multi-modal transport to be competitive with uni-modal truck transport.

Stochastic Network Design for Planning Scheduled Transportation Services: The Value of Deterministic Solutions

We study the value of deterministic solutions, in particular their quality and upgradability, in addressing stochastic network design problems, by analyzing their time-dependent formulations known as scheduled service network design problems in freight transportation planning. We study several problem variants and models and investigate, for each case, the immediate quality of the deterministic solutions stemming from the 50th and the 75th percentile of the demand distributions. We then show that for all models, but in different ways, we are able to make effective use of parts of the deterministic solution, confirming the value of the deterministic solution in the stochastic environment, even when the deterministic solution itself performs badly. We also investigate what makes the optimal stochastic solution better in the stochastic environment than other feasible solutions, particularly those obtained by addressing deterministic versions of the problem. We do this by quantitatively analyzing the structures of different solutions. A measurement scheme is proposed to evaluate the level of potentially beneficial structural properties (multipath usage and path sharing) in different solutions. We show that these structural properties are important and correlated with the performance of a solution in the stochastic environment. Data and the online appendix are available at https://doi.org/10.1287/ijoc.2018.0819 .

Optimal Allocation of Rolling Stock in Scheduled Transportation Services

Passenger railway transportation services are operated in cyclic periodicities for urban and long distance traffic. Cabins and locomotives (rakes) are assigned to each service for specified time duration to operationalise timetables. Such resource allocations are generally constrained and incur cost, each in travel time, empty cabin runs and rake compositions. Some constraints are safety related and others are desirable for performance improvement. Resource utilisation is effective, if demands are met; efficient, if utilisation cost is minimum. A multi-commodity network flow model is presented to optimally allocate rolling stock, to fulfil demands at minimum operational cost. However, the model is computationally expensive and a relaxed model using simulation based heuristic is presented. Real data from Indian railways is used for testing. The problem context, model, heuristic approach and solutions are reported. Managerial insights that emerged from this empirical study are interesting; we present them along with limitations and possible extensions.

Optimal allocation of rolling stock in scheduled transportation services

Optimal allocation of rolling stock in scheduled transportation services

Measuring Transportation System Resilience: Response of Rail Transit to Weather Disruptions

AbstractMajor disruptions of transportation systems due to severe weather events such as hurricanes, storm surges, and flooding are becoming more common. A logical response is to make those systems better able to withstand and rebound from large-scale weather assaults. Resilience is the term commonly used to describe this property of transportation systems, and while there are numerous definitions of resilience, there is no commonly used metric to characterize it. This paper reviews the concept of resilience in different fields and offers a definition that encompasses three common strategies for making transportation systems more resilient: hardening, redundancy, and elasticity. The paper offers a graphical and analytic metric for assessing the resilience of scheduled transportation services in the face of weather disruptions, focusing on heavy rail transit (HRT) systems. The concept of planned service days lost to weather disruptions is suggested as a useful aggregate measure of system resilience that is...

Modeling and solving a multimodal transportation problem with flexible‐time and scheduled services

AbstractThis article studies a transportation problem in a multimodal network with shipment consolidation options. A freight forwarder can use a mix of flexible‐time and scheduled transportation services. Time windows are a prominent aspect of the problem. For instance, they are used to model pickup and delivery time slots. The various features of the problem can be described as elements of a digraph and their integration leads to a holistic graph representation. This allows an origin‐destination integer multi‐commodity flow formulation with nonconvex piecewise linear costs, time windows, and side constraints. Column generation algorithms are designed to compute lower bounds. These column generation algorithms are also embedded within heuristics aimed at finding feasible integer solutions. Computational results with real‐life data are presented and show the efficacy of the proposed approach. © 2010 Wiley Periodicals, Inc. NETWORKS, 2011

Scheduled service versus personal transportation: The role of distance

This paper presents a theoretical and empirical analysis of the relationship between frequency of scheduled transportation services and their substitutability with personal transportation (using distance as a proxy). We study the interaction between a monopoly firm providing a high-speed scheduled service and private transportation (i.e., car). Interestingly, the carrier chooses to increase the frequency of service on longer routes when competing with personal transportation because by providing higher frequency (at extra cost) it can also charge higher fares which can boost its profits. However, in line with the results of earlier studies, frequency decreases for longer flights when driving is not a viable option. An empirical application of our analysis to the European airline industry confirms the predictions of our theoretical model.

Scheduled Service Versus Personal Transportation: The Role of Distance

This paper presents a theoretical and empirical analysis of the relationship between frequency of scheduled transportation services and their substitutability with personal transportation, using distance as a proxy. We study the interaction between a monopoly fi rm providing a high-speed scheduled service and private transportation (i.e., car). Interestingly, the carrier chooses to increase the frequency of service on longer routes when competing with personal transportation because by providing higher frequency (at extra cost) it can also charge higher fares which can boost its profi ts. However, in line with the results of earlier studies, frequency decreases for longer flights when driving is not a viable option. An empirical application of our analysis to the European airline industry confi rms the predictions of our theoretical model.

Twenty years of airline deregulation: the impact on outlying small communities

Many rural communities over the years have had to endure reduced levels of scheduled transportation services to the point that some have indeed experienced a cessation of services. Accompanying the deregulation of airlines in 1978 was the expressed fear that transportation services would continue to spiral downward and various communities would lose their population bases. This study investigates the two decades of airline deregulation and the impact that that 1978 legislation has had on small communities that are situated 100 air miles or more from any hub airport. Chief among the findings are: (1) that service levels have indeed deteriorated as indicated by the fact that over one-quarter of the non hubs lost all service, (2) of those locations that retained some service, nearly two-thirds experienced reduced levels of service, and (3) the overall pattern of population growth remained approximately the same whether service was eliminated, reduced, or increased.

Reliability of interconnected scheduled services

In this paper we consider the performance of interconnected scheduled transport services for which the service times have a significant random element. That is, the arrival and departure times vary randomly from trip to trip. Any delay to a service can affect its punctuality at later stops and can affect all following services. For specificity we refer mainly to scheduled train services throughout. The reliability and performance of schedules is often investigated by stochastic simulation. However, by adopting a more analytic approach we are able to: (a) derive some properties of various measures of performance and, (b) more easily find improved or optimized schedules. Both (a) and (b) can be difficult or intractable using a simulation approach. We define various measures of reliability and performance for scheduled services, and show how to compute these. We also show how to compute or adjust schedules so as to satisfy reliability goals or targets, or optimize costs or benefits, including reliability costs. We derive various properties of these measures of reliability. In particular, we consider how reliability and costs vary in response to varying the scheduled trip times and station dwell times, or arrival and departure times. To ensure generality, we do not specify any particular forms for any of the distributions of trip times, etc.—they can be theoretical or empirical.

A Simple Analysis of Optimal Fares on Scheduled Transport Services

A Simple Analysis of Optimal Fares on Scheduled Transport Services